1. Field of the Invention
The present invention relates to Quality of Service (QoS) for packet traffic and, more particularly, to QoS guarantee for packet traffic transiting through more than one sub network also referred to as Autonomous System (AS).
2. Description of the Related Art
At the moment there is a trend toward all-Internet Protocol (IP) communication. However, IP has been based on a best effort paradigm by which traffic is served in a first-in first-out (FIFO) manner. The problem comes from the fact that time-affected services require a minimal quality of service (QoS) guarantee. Many solutions were developed to address the problem. In the end, it all aims at getting the best performance from the network while optimizing its resource utilization. That is often referred to as traffic engineering. Most traffic engineering techniques are based on the assumption that the engineered traffic will remain within one or few networks under a common administration. However, research shows that most time-affected services usually span across two to eight autonomous systems (AS). This implies that traffic engineering techniques need to support the traffic across more than one AS.
Unfortunately, little work has been done in the inter-AS or inter-domain traffic engineering field. Many techniques rely on the use of Border Gateway Protocol (BGP), which is the inter-domain routing protocol used in IP networks. BGP is defined at length by the Internet Engineering Task Force (IETF) under the Request For Comment (RFC) number 1771 and 1772, which is herein included by reference. The current inter-domain traffic engineering techniques make use of common BGP path attributes to prefer some inter-domain routes to others. However, these techniques do not provide sufficient reliability to support time-affected services, which require a QoS guarantee not only from each of the traversed AS, but also on an overall end-to-end perspective. Moreover, some further aspects of an acceptable solution are not present in the current inter-domain traffic engineering techniques. For instance, there is a lack granularity that prevents per flow discrimination of QoS.
As can be appreciated, the current inter-domain traffic engineering techniques fall short at providing a QoS reservation and packet forwarding solution that would fulfill the needs of time-affected services that are provided over multiple AS.